The Science-Backed Reason Why Drinking Diet Soda Makes You Hungrier

In theory, the solution to satisfying hunger is straightforward: You eat something and your hunger goes away. In reality, it’s not that simple. You’ve probably experienced firsthand how some meals fill you up more than others, even if it’s the same amount of food. (Exhibit A: Finding yourself reaching back into the fridge an hour after you had a heaping plate of lo mein.)

Sometimes, it’s not the nutrient density (or lack thereof) of your meal that can get in the way of satisfying your hunger pangs; it could be the drink you’re pairing your meal with.

According to a new scientific study published in the journal Nature Metabolism, non-caloric sweeteners (often found in diet sodas and other drinks) mess with the brain’s response to hunger and satiety. That means they can make it harder to know when you’re actually full. In fact, they could even make you feel hungrier.

To learn more about how these common types of sweeteners interrupt hunger cues, we talked to the lead study author as well as doctors who specialize in understating hunger and satiety. Especially if you find yourself feeling hungry all the time, their insight can help you understand the key to truly feeling satiated.

The main reason sugar substitutes like aspartame, sucralose, stevia and erythritol are popular is simple: Unlike sugar, they don’t have any calories. This is why you’ll find them in a lot of diet soda drinks, as well as many other processed foods and drinks labeled as low-calorie or zero-calorie. The problem is that consuming these types of sweeteners confuses the brain.

“The brain is perceiving that there should be calories coming in, but there isn’t. Since there are no calories coming in, the brain increases appetite for consumption of other calories,” explained Dr. Nicholas Pennings, a family medicine and obesity medicine doctor and the Director of Campbell University Health Center.

Dr. Hector Perez, a bariatric surgeon at Renew Bariatrics, put it this way: “Simply put, it seems like non-caloric sweeteners confuse your brain. You’re programmed to expect some extra calories when you eat something sweet, and non-caloric sweeteners don’t fulfill that expectation. This mismatch stimulates your brain’s hunger signals and you end up eating more than you normally would,” he said.

Dr. Kathleen Page, the Director of the USC Diabetes and Obesity Research Institute and the lead author of the Nature Metabolism study, told HuffPost that while artificial sweeteners can confuse hunger cues for everyone, certain people experience it to a greater effect. Her study found that both women and people with obesity had a heightened response to the non-caloric sweetener. She said that the difference between people with obesity and people without obesity was especially pronounced. “People with obesity had a really strong response in the hypothalamus, which is the part of the brain that regulates hunger,” Page said. This means that people with obesity who drink diet soda are more likely to overeat than people without obesity who drink diet soda because their brain is doing a worse job of regulating their hunger pangs.

Why people with obesity are more greatly impacted is a mystery. “It’s like a chicken or egg situation,” Page said. “It could be a cause or consequence of obesity. We really don’t know.” Perez added to this, saying, “As a bariatric surgeon dealing with chronically obese people, I always stress the fact that being overweight is only the tip of the iceberg when it comes to obesity. A lot of bodily functions are affected, and you’re not the same as a person with a healthy weight. This includes your brain and how it responds to food.”

Whether you are trying to avoid overeating or just want to be able to better understand if you’re truly hungry or not, all three experts recommend avoiding diet sodas and other products with non-caloric sweeteners. If you are trying to lose weight, Pennings told HuffPost he recommends avoiding both sugar and non-caloric sweeteners. This is because sugar consumption is linked to weight gain and non-caloric sweeteners can cause you to eat more than you would otherwise.

There are other factors that can mess up your hunger cues, too. Scientific research shows that hunger and thirst can be easily confused. “Our bodies sometimes send the same signals for hunger and thirst because the mechanisms overlap and recognizing that can prevent unnecessary snacking,” Perez said. With that in mind, staying well-hydrated can help you figure out if you’re truly hungry or if you just need to drink some water.

If you feel hungry all the time, it may be because you aren’t consuming nutrients that are satiating, like protein, complex carbohydrates, fiber and unsaturated fats. Scientific research also shows that not getting enough sleep, having high levels of stress and eating while you’re distracted (such as while you’re at your computer or watching TV) can all make it harder to know when you’re full and are linked to overeating too. “Practice mindful eating — chew slowly, savor each bite and check in with yourself periodically during meals. Over time, this helps you rebuild trust in your natural hunger signals and builds healthier habits,” Perez said.

Sure it’s none of the above? Book an appointment with your health care provider to make sure there isn’t an underlying health condition or side effect of a medication that could be causing your constant hunger. For example, Perez told HuffPost that antidepressants and blood pressure medications can both mess with hunger cues.

With all this in mind, figuring out whether you’re hungry or not is clearly a little more complicated than it seems on the surface. In a perfect world — where everyone eats nutrient-rich foods and nothing artificial, focuses on their meals, gets enough sleep, isn’t stressed out and stays well-hydrated — the brain is great at communicating to you whether you’re hungry or not. But since none of us live in this perfect world, it takes more work to decipher. Minimizing diet sodas is one step in the right direction.